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OK to Park a DC Loco on DCC Powered Track?

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OK to Park a DC Loco on DCC Powered Track?
Posted by peahrens on Friday, December 21, 2012 4:24 PM

HI. I received a DC (DCC ready) Kato Alco RS-2 (used) today and will in the future convert it to DCC.  Can I park it on my DCC (NCE) powered layout to look at, or can that be bad for the loco or the DCC system?

Thanks.

Paul

Paul

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Posted by Jacktal on Friday, December 21, 2012 4:37 PM

Definitely not.Non decoder equipped locos should NEVER be left on DCC powered tracks.The motor does get continuous power and this will destroy it.

DC powered locos can be run on DCC with some systems on adress 00 (don't know about NCE) but still,they have to be removed from the track after use.

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Posted by jrbernier on Friday, December 21, 2012 4:49 PM

  Depending on the motor, severe damage can be done to it.  I ran a DC powered Bachmann trolley on a Christmas Tree loop with no problems, but it does make a strange 'singing' sound as the it runs.  I would not do this with a new model.  Your NCE system does not support 'zero stretching' and I have heard of at least a couple of guys who fried the motor in non-DCC models.

Jim

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Posted by cacole on Friday, December 21, 2012 4:49 PM

As Jacktal said, never put a DC powered locomotive on a DCC track and leave it for any extended period of time, because this will cause the motor to overheat and be destroyed.

NCE does NOT allow a non-DCC motor to run on DCC on address 00, and the NMRA should never had allowed this in their DCC Standards and Recommended Practices due to motor overheating issues.

Decoders are down in price to $12 each in bulk lots of 10 if you know where to shop online.  When the NMRA adopted their DCC Standards and Recommended Practices decoders cost nearly $75 each, and they thought they were doing modelers a favor with the zero-stretching gimmick.

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Posted by stilson4283 on Friday, December 21, 2012 4:50 PM

Nope, the AC like signals of DCC can ruin your motor, you can here the humming when you place the locomotive on the tracks.  

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Posted by richhotrain on Friday, December 21, 2012 4:57 PM

peahrens

HI. I received a DC (DCC ready) Kato Alco RS-2 (used) today and will in the future convert it to DCC.  Can I park it on my DCC (NCE) powered layout to look at, or can that be bad for the loco or the DCC system?

Park it on an isolated (gapped) unpowered siding if you want to just look at it.

Rich

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Posted by peahrens on Friday, December 21, 2012 5:10 PM

Thanks, folks (glad I asked!).  I will not fry it by parking it on hot track.

IF I decide to make this a DCC & sound loco (so far I have no DCC w/o sound) I'd likely have my LHS do it, after understanding how the speaker arrangement and sound quality were likely to turn out.  Ideally, all my locos would have sound. 

But, if I decide to have some DCC w/o sound locos that creates lots more options.  I'd likely try that myself (if plug-in like this one) but would the decoder also handle the lighting via the plug-in or would I need to swap the light and/or wire it specially?  (Guess I need to dive into the book I bought!)

  

Paul

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Posted by rrinker on Friday, December 21, 2012 5:12 PM

 Funny how the responses every time this topic comes up are SO predictable.

Those with systems that can use zero stretching say "ok, just be careful, don't leave the loco standing still"

Those with system that can't do this seem to be of tha attitude that it will instantly destroy your loco and should never have been allowed.

 NCE originally supported it, but you had to make your own throttle to run address 00 that plugged in to the serial port ont he Powerhouse Pro command station. The feature was removed some years ago in a firmware update.

 I find it very handy for test runnign new locos before adding a decoder. Haven't burned one up yet, but I don;t leave a non-decoder loco parked on the track just sitting there. Some motors make more noise than others - Athearn with their loosely assembled motors sing quite loudly, Kato and Atlas motors are not so noisy. I've used the strong pulse effect to free up a built up but never run Bowser PRR T1, all it did on my DC power pack was short out, managed to get it to turn over on the DCC track and after a few trips around the layout in each direction it started to work itself out and run like it should.

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Posted by retsignalmtr on Saturday, December 22, 2012 5:45 AM

I have a pair of N scale Atlas GP7's that I occasionally run on DCC. I like the sound the loco's make when run on DCC. It sounds like an EMD accelerating and decelerating. I left one of them on powered track for about 1 1/2 hour and when trying to run it again it wouldn't run at all. the motor was very warm and I couldn't turn it by rotating ther worm gears. Later when the motor cooled down it ran fine and continues to do so today.

Do not leave a DC loco on powered track. They may creap along on their own and may overheat.

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Posted by richhotrain on Saturday, December 22, 2012 6:00 AM

Whenever I acquire a DC loco, before installing the decoder, I test run the DC loco on a length of track powered by a DC  power pack.  Does the loco run forward and backward?  Do the lights work?  If so, then I am ready to install the decoder, but first I test the decoder on my NCE DTK decoder tester.

I never put a DC loco on any DCC powered track.

Rich

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Posted by JoeinPA on Saturday, December 22, 2012 7:57 AM

Rich:

I do what you do except that I use a wheel roller setup that I got from MicroMark. I run the engine forward for a while and in reverse for a while. That way I can loosen it up and detect any problems that develop on running. I also watch the amp draw to see if the motor is performing OK.

Joe

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Posted by aj1s on Sunday, December 23, 2012 10:54 PM

For those that have systems that support analog locos at address 0, what happens if you do not command  address 0 to speed zero before you put a DC loco on the track? Do these systems always zero-stretch to maintain zero volts DC on the track, unless/until non-zero speed commands are issued to address 0?

Just curious. I'm in the NCE camp, so naturally I think it is a practically useless and potentially dangerous feature that could even put your eye out! :)

Andy

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Posted by rrinker on Monday, December 24, 2012 10:37 AM

 As long as address 0 is at a non-zero speed, there is a DC potentical to the track signal and a DC loco will start moving, just like when you don;t turn the power pack throttle to stop.

 It's really only dangerous to leave a non-decoder loco sitting still and not turning. That's when it will heat the most. When the armature is turning, there's some airflow to help cool it. Only coreless motors cannot handle any operation like this, those motors will be quickly destroyed. But they will also be destroyed with a decoder installed if the decoder is not a high frquency or silent running type. Most any current decoders are, but the Bachmann motor only ones generally aren't, and many older deocders did not have this feature, the sharp low frequency ulse drive from those decoders causes the same sort of heating in a coreless motor.

                    --Randy

 


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Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by aj1s on Wednesday, December 26, 2012 12:34 PM

Randy,

Thanks. I understand the stalled rotor heating problem. That's not the root of my question (but thanks for the explanation, since it may help others).

Pardon my ignorance, but most people suggest disabling analog mode on mobile encoders to avoid issues with runaway locomotives sometimes occurring at power-on. 

Is this because DC track voltage is NOT always maintained at zero at startup, or something else?

Are boosters required to automatically maintain track voltage at 0 volts DC unless/until they have a viable control input? Do any boosters maintain 0 VDC in the absence of a valid control bus input?

While the motor overheating will not "instantaneously" destroy a loco, running at very high speed could cause the loco to take an unplanned route down an extreme grade, and destroy it quickly enough that it might as well be considered "instantaneously"!

Such a scenario might not be the fault of a DCC component per se (more likely a bad wiring connection, broken/disconnected connector, etc.), but running a DC loco on DCC removes one of the "safeties" inherent in the system. Just like the ground wire in (US) electrical systems. that extra measure of safety is never needed unless something else goes wrong. 

Also, another message thread here just brought up the issue of reverse loops, AR controllers, and DC locomotives on DCC layouts. They don't play nicely with each other. You can't exit an AR controlled reverse loop into a non-AR controlled district with a DC loco. 

As an NCE camper, naturally I'll add that to my "list of reasons running DC locos on DCC power is a bad idea" Big Smile

Andy

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Posted by Mark R. on Wednesday, December 26, 2012 1:14 PM

On a DCC system, there is no form of DC voltage on the rails of any kind. The DCC track voltage is very similar to an AC sine wave but at a much higher frequency. The decoder is what converts this AC-like voltage to a usable DC for the motor circuit.

When you place a DC engine on a track with DCc voltage, you are in essence applying a low pulse AC voltage to the motor. An AC voltage is an equal pulsing of positive and negative at a very high frequency. So, at speed step 0, the DC motor is receiving small equal pulses of opposing voltages at about 120 time per second. This means the motors armature is occilating back and forth 120 time per second .... this is the buzzing sound you are hearing.

What zero stretching does is either increase the positive or negative amplitude of the AC sine wave. The armature is still occilating back and forth 120 time persecond, but it's occilating ever so slightly more in one direct than the other the higher the amplitude is, creating rotational movement.

This would be the same as you sitting there and throwing the direction switch on your DC power pack 120 times per second .... not that you could actually do that, but that's what's happening to your DC motor when being controlled by a DCC signal .... not good for it by any means.

 

Mark. 

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Posted by rrinker on Wednesday, December 26, 2012 1:21 PM

 On initial power up, the DCC signal may not be fully formed for a few cycles - if the decoder is set to do analog conversion, it might see this as DC and take off. I've not had this happen, but I started disabling DC in the decoders anyway _ I'll never run them with DC, so I'll proactively avoid any potential problem.

 

                 --Randy

 


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Posted by jalajoie on Wednesday, December 26, 2012 1:25 PM

Personally I don't run a DC loco on a DCC system, however at my club we had a member that never installed a decoder into his engines. He ran analog locos on our Digitrax system for 10 years without any ill effect to ether his locos or the Digitrax system. In fact he was so good at running his trains that he could even run through a reversing loop with ease. He knew the exact time he had to reverse the direction on the throttle to achieve that feat.

This member never had any failure to his roster running constantly analog locos on a DCC system.

Jack W.

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Posted by Mark R. on Wednesday, December 26, 2012 1:30 PM

aj1s

Randy,

Thanks. I understand the stalled rotor heating problem. That's not the root of my question (but thanks for the explanation, since it may help others).

Pardon my ignorance, but most people suggest disabling analog mode on mobile encoders to avoid issues with runaway locomotives sometimes occurring at power-on. 

Is this because DC track voltage is NOT always maintained at zero at startup, or something else?

Are boosters required to automatically maintain track voltage at 0 volts DC unless/until they have a viable control input? Do any boosters maintain 0 VDC in the absence of a valid control bus input?

While the motor overheating will not "instantaneously" destroy a loco, running at very high speed could cause the loco to take an unplanned route down an extreme grade, and destroy it quickly enough that it might as well be considered "instantaneously"!

Such a scenario might not be the fault of a DCC component per se (more likely a bad wiring connection, broken/disconnected connector, etc.), but running a DC loco on DCC removes one of the "safeties" inherent in the system. Just like the ground wire in (US) electrical systems. that extra measure of safety is never needed unless something else goes wrong. 

Also, another message thread here just brought up the issue of reverse loops, AR controllers, and DC locomotives on DCC layouts. They don't play nicely with each other. You can't exit an AR controlled reverse loop into a non-AR controlled district with a DC loco. 

As an NCE camper, naturally I'll add that to my "list of reasons running DC locos on DCC power is a bad idea" Big Smile

Andy

Andy, there's a good reason for dis-abling the analog (DC) mode on a decoder. When a decoder is first powered up, there's a process the processor goes through called "check sum". This process checks all the parameters of the decoder and happens in just a fraction of a second. This process also checks to see what kind of voltage is present on the rails (DC / DCC / Motorola / etc.) and will then acknowledge this as the voltage configuration to be used. There is no DC voltage on the rails of a DCC system of any kind. 

If this check sum process hiccups and doesn't see the DCC voltage, it will automatically default to a DC voltage. Seeing as how most DCC systems have around 14 volts (generically speaking) on the rails, the engine takes off at what the decoder thinks is 14 volts DC. By turning off the ability of the decoder to run on DC, the check sum process will not default the input signal to DC if it misses the DCC signal in the start-up process.

The same happens to momentary losses of power no matter how instantaneous - upon re-application of power, the check sum checks the track input. Again, this takes a very small fraction of a second to do this. Again, that's why an engine will just take off for no apparent reason - you hit a small piece of dirt, the check sum process missed the DCC signal, told the decoder it was DC and the engine took off.

If you regularly run your engine on DCC, turn the analog mode off to prevent this. It's easy enough to change CV29 by one digit if you want to run it on a DC layout any time.

 

Mark.  

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Posted by csxns on Wednesday, December 26, 2012 7:59 PM

jalajoie
He ran analog locos on our Digitrax system for 10 years without

Is this Digitrax,wireless?

Russell

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Posted by jalajoie on Wednesday, December 26, 2012 8:56 PM

csxns

jalajoie
He ran analog locos on our Digitrax system for 10 years without

Is this Digitrax,wireless?

Yes it is a DCS200  8amp. wireless system. It was installed at the club in 1999 and has been working like a swiss clock ever since.

Jack W.

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Posted by csxns on Thursday, December 27, 2012 9:26 AM

Thanks.

Russell

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Posted by hobo9941 on Thursday, December 27, 2012 11:41 PM

DCC puts a constant AC voltage on the tracks. The rapid reversal in direction of a DC loco, 60 times a second, is hard on the gears.Whistling

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Posted by joe323 on Friday, December 28, 2012 7:49 AM
You could do what i did and build a small layout for display only I keep my dc locos and surplus rolling stock on there and switch out the rolling stock once in a while I do not bother with the 6 locos since the 7 dcc ones I have are more than enough for the main layout. However I keep the dc locos on display for sentimental reasons.

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Posted by richg1998 on Saturday, December 29, 2012 4:46 PM

jalajoie

Personally I don't run a DC loco on a DCC system, however at my club we had a member that never installed a decoder into his engines. He ran analog locos on our Digitrax system for 10 years without any ill effect to ether his locos or the Digitrax system. In fact he was so good at running his trains that he could even run through a reversing loop with ease. He knew the exact time he had to reverse the direction on the throttle to achieve that feat.

This member never had any failure to his roster running constantly analog locos on a DCC system.

Notice he said running not sitting still while on DCC.

I have run DC motors on DCC and the armature was cooler while running. The armature got hotter, the longer the motor was sitting still. I used an infra red temp scanner for the measurements.

Remember, your mileage will vary.

Rich

N

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Posted by geomodelrailroader on Wednesday, June 06, 2018 5:24 PM

If it is a kit convert it as soon as possible. You should never place a DC locomotive on live DCC track the only place you place them is on insilated programming tracks or on a section wired to DC. If you place a DC locomotive of DCC track it will blow up same thing happens to older locomotives. 

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Posted by cuyama on Wednesday, June 06, 2018 5:27 PM

geomodelrailroader
If it is a kit convert it as soon as possible. You should never place a DC locomotive on live DCC track the only place you place them is on insilated programming tracks or on a section wired to DC. If you place a DC locomotive of DCC track it will blow up same thing happens to older locomotives. 

5-year-old thread; and your reply is not fully correct. Some DCC systems (like Digitrax) do allow most DC locomotives to operate without harm for a short time. The programming track has nothing to do with DC operation.

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Posted by joe323 on Thursday, June 07, 2018 6:44 AM

What CV disables DC mode on DCC loco and what setting should it be to disable it?

Joe Staten Island West 

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Posted by rrinker on Thursday, June 07, 2018 7:14 AM

 It's part of CV29, bit 2 (so value of 4). Not so simple as just subtracting 4, but common values of CV29 are 38 and 6, for long address or short address. In those cases, making it 34 or 2 will turn off DC operation in the decoder.

Digitrax command statioons also have an option to turn off the ability to run an analog loco. On a layout with only a few trins runnign it doesn't really matter but on a busy layout, running an analog loco using address 00 slows the response of all the others because it works by making every 0 bit in the DCC data stream longer, which means each data packet takes longer to send, so it takes longer for a command to get froom the throttle to a DCC loco. Most clubs disable the analog in the command station for this reason.

 Disabling it int he loco means you can;t take your DCC loco and run it on a friend's DC layout, but it also can prevent runaways where when the layout is powered up, the DCC signal isn't fully formed so the loco thinks it is on DC and takes off at full speed. Disabling DC in the decoder stops this.

 The harsh pulses of DCC driving a DC loco actually worked out for me once - had an old Bowser PRR T1 that had never been run after being built, and none of the DC packs I had could get it ti run and keep running, they didn;t have enough power. Put it on the DCC track using address 00 and it was able to move and keep moving long enough to finally start breaking in, gradually got faster and smoother. The big heavy motor in that wasn;t in much danger running on the DCC track, but to leave it sitting there NOT spinning would eventually overheat it or any motor.

                                     --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by BigDaddy on Thursday, June 07, 2018 7:22 AM

joe323
What CV disables DC mode on DCC loco and what setting should it be to disable it?

Bit 2 of CV 29

I don't know how to change a single bit and I'll bet you don't either.  That's why Al Kalmbach invented the CV 29 calculator  

http://www.digitrax.com/support/cv/calculators/

Analog is the highfalutin word for DC

Henry

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Posted by maxman on Thursday, June 07, 2018 9:26 AM

BigDaddy
That's why Al Kalmbach invented the CV 29 calculator

"I don't think so, Tim"

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